iommu: Introduce direct mapped region handling

Add two new functions to the IOMMU-API to allow the IOMMU
drivers to export the requirements for direct mapped regions
per device.
This is useful for exporting the information in Intel VT-d's
RMRR entries or AMD-Vi's unity mappings.
Signed-off-by: Joerg Roedel <jroedel@suse.de>

drivers/iommu/iommu.c

@@ -1469,3 +1469,19 @@ int iommu_domain_set_attr(struct iommu_domain *domain,
 	return ret;
 }
 EXPORT_SYMBOL_GPL(iommu_domain_set_attr);
+
+void iommu_get_dm_regions(struct device *dev, struct list_head *list)
+{
+	const struct iommu_ops *ops = dev->bus->iommu_ops;
+
+	if (ops && ops->get_dm_regions)
+		ops->get_dm_regions(dev, list);
+}
+
+void iommu_put_dm_regions(struct device *dev, struct list_head *list)
+{
+	const struct iommu_ops *ops = dev->bus->iommu_ops;
+
+	if (ops && ops->put_dm_regions)
+		ops->put_dm_regions(dev, list);
+}

include/linux/iommu.h

@@ -114,6 +114,20 @@ enum iommu_attr {
 	DOMAIN_ATTR_MAX,
 };
 
+/**
+ * struct iommu_dm_region - descriptor for a direct mapped memory region
+ * @list: Linked list pointers
+ * @start: System physical start address of the region
+ * @length: Length of the region in bytes
+ * @prot: IOMMU Protection flags (READ/WRITE/...)
+ */
+struct iommu_dm_region {
+	struct list_head	list;
+	phys_addr_t		start;
+	size_t			length;
+	int			prot;
+};
+
 #ifdef CONFIG_IOMMU_API
 
 /**
@@ -159,6 +173,10 @@ struct iommu_ops {
 	int (*domain_set_attr)(struct iommu_domain *domain,
 			       enum iommu_attr attr, void *data);
 
+	/* Request/Free a list of direct mapping requirements for a device */
+	void (*get_dm_regions)(struct device *dev, struct list_head *list);
+	void (*put_dm_regions)(struct device *dev, struct list_head *list);
+
 	/* Window handling functions */
 	int (*domain_window_enable)(struct iommu_domain *domain, u32 wnd_nr,
 				    phys_addr_t paddr, u64 size, int prot);
@@ -205,6 +223,9 @@ extern phys_addr_t iommu_iova_to_phys(struct iommu_domain *domain, dma_addr_t io
 extern void iommu_set_fault_handler(struct iommu_domain *domain,
 			iommu_fault_handler_t handler, void *token);
 
+extern void iommu_get_dm_regions(struct device *dev, struct list_head *list);
+extern void iommu_put_dm_regions(struct device *dev, struct list_head *list);
+
 extern int iommu_attach_group(struct iommu_domain *domain,
 			      struct iommu_group *group);
 extern void iommu_detach_group(struct iommu_domain *domain,
@@ -379,6 +400,16 @@ static inline void iommu_set_fault_handler(struct iommu_domain *domain,
 {
 }
 
+static inline void iommu_get_dm_regions(struct device *dev,
+					struct list_head *list)
+{
+}
+
+static inline void iommu_put_dm_regions(struct device *dev,
+					struct list_head *list)
+{
+}
+
 static inline int iommu_attach_group(struct iommu_domain *domain,
 				     struct iommu_group *group)
 {